Abstract
Imperforate hymen is a rare congenital malformation of the female genital tract. The condition poses several diagnostic challenges owing to its low incidence and often atypical presentation. Classical symptoms include amenorrhoea and cyclical abdominal pain. Delayed diagnosis leads to potentially irreversible and lifechanging sequelae including infertility, endometriosis and renal failure. A premenarchal 13-year-old girl with a background of chronic constipation presented with symptoms mimicking acute appendicitis. The underlying cause was imperforate hymen and retrograde menstruation. The diagnosis was made during diagnostic laparoscopy. As with this patient, pre-existing symptoms are often troublesome long before the true diagnosis is made. This case report highlights the importance of recognising imperforate hymen as a potential cause of acute abdominal pain in premenarchal adolescent girls. The clinical picture may present as right or left iliac fossa pain. Early identification reduces the risk of adverse complications and avoids unnecessary and potentially harmful interventions.